SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b35a8b100e34d775c5e4b5fdffe6ea45255ca5fb06b71f3af8f9de8d9f8e238f' 
  AND token = 'QiWFpXIO7tVPjrogUPOQT4sP88DK/pTZqdsGIG2b97g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}